SDS grounded conductors

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slipknotbmg

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I need help (code ref., Prof. opinions, facts) backing up an issue on a machine we are installing.

Here is the situation: 480v 5/w feeder, (1)277v/230v xfmr. (1)277v/120v xfmr., both fed from 1 leg of feeder. XO bonded at both xfmr. secondarys. CE rated (no UL) xfmrs. pri./sec. nuetral internally connected. Both xfmr. secondary neutrals tie to a common terminal strip in control panel.

I had proposed replacing the CE rated xfmr.s w/ UL and separating the neutrals. Citing #1 - no UL and #2 - unbalanced return flow to each SDS that would possibly cause issues w/ the computers on the machine, I.E. timers, counters etc. I have yet to turn this system on and will not until I have the facts. Needless to say, this has caused a stink, as the German Co. who made the mach. says it is fine the way it is, and if I replace the xfmrs. and rewire I will void the warranty. I need to know if I am correct and if so, I need ref's. to back it up. Any help would be greatly appreciated.
 
Re: SDS grounded conductors

my 1st question, perhaps not the most important, would be does the machine have a third party certification at all ? being German, it may not have "U.L.", but there is a German counterpart for U.L.
From a circuitry standpoint, I don't see a problem, but perhaps I'm overlooking something.
If the equipment is aceeptable to the AHJ, and if changing it voids the warranty and listing, I'd leave well enough alone.
 
Re: SDS grounded conductors

Plus, if it came with instructions for installation and you don't install it as designed, you are in violation of 110.3(B)

Just a thought.
 
Re: SDS grounded conductors

Plus, if it came with instructions for installation and you don't install it as designed, you are in violation of 110.3(B)

Just a thought.
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Thanks bdarnell, as I said any help would be greatly appreciated, and I did install it as it was designed. However I will not turn it on w/o a UL approval or testing by a certified alternate. I don't see how, in this case I would be in violation of 110.3(B) If I buy a ext. cord at the dollar store that was made in China w/o U.L. approval, and the instructions were to plug it in, would it be a violation to refuse to plug it in?

Augie, what is the German counterpart for U.L. and is it accepted here in the U.S.?
 
Re: SDS grounded conductors

Are you going to replace every device on the machine that does not have an individual UL label, or just the transformers?

It is hard to visualize your installation.

Each transformer is fed with a primary line conductor and a grounded conductor (what you are calling the neutral)? This is fine.

Each transformer has a secondary conductor which is grounded through a bonding jumper? This is acceptable wiring.

There is an internal bonding connection between the primary grounded conductor and the secondary grounded conductor? If this is true it would cause the primary grounded conductor to be bonded to ground at two locations and it would be a code violation.
 
Re: SDS grounded conductors

Are you going to replace every device on the machine that does not have an individual UL label, or just the transformers?
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No, everything else is IEC w/ dual CE/UL listings.

Each transformer is fed with a primary line conductor and a grounded conductor (what you are calling the neutral)? This is fine.
Click to expand...
Yes

Each transformer has a secondary conductor which is grounded through a bonding jumper? This is acceptable wiring
Click to expand...
Also yes

There is an internal bonding connection between the primary grounded conductor and the secondary grounded conductor? If this is true it would cause the primary grounded conductor to be bonded to ground at two locations and it would be a code violation.
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This is also true, added to the fact that each secondary Grounded Conductor from each xfmr., runs to a common terminal strip where they are tied together, two SDS grounded conductors tied to the same point. This is where I assume there would be a issue.
 
Re: SDS grounded conductors

Does the machine have electric motors?

They are never UL listed.

Has anyone asked for the listing?

I do not know of any requirement for listed transformers only approved.
 
Re: SDS grounded conductors

I do not see an inherent problem with the grounded conductors of different SDSs being tied together at a common terminal strip. After all they should all be bonded to "ground" anyway.

I have a problem with the bonding of the primary grounded conductor at a second point in the system.
 
Re: SDS grounded conductors

Not specifically, but rather because it violates 250.24(A)(5) and 250.30(A) when an additional bond is made at the secondary terminals per 250.30(A)(1).

But, because you have a "solidly connected grounded circuit conductor" you do not have a seperately derived system so a 250.30 bond is not required on the secondary.
 
Re: SDS grounded conductors

Augie, what is the German counterpart for U.L. and is it accepted here in the U.S.?
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I'm sorry,I don't recall. This issue came up at a local industrial facility a few years back on German and Japenese equipment and I was able to confirm there was a recognized third party testing facility...but the name is long forgotten (it was german and involved the word "government") I was in hopes someone on the forum had better memory or more recent experiences.
 
Re: SDS grounded conductors

The largest testing lab in the world is TUV.

VDE is the German standards group similar to our ANSI.
 
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